Smiley War: Angel x Devil v11.0

Play one of greatest games, Smiley - angel vs. devil! A variation of the classic "Lights out" game!
The game is simple, you have to turn all the devils into angels, can you do that? Only one way to find out!

Hint:
Click until you found a configuration which has a
diagonal symmetry axis. After that click always the
same on both sides of the diagonal symmetry axis.
This keeps the symmetry until you find a solution.